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Shimano Goes 10 Speed for XT, SLX with New Dynasys Tech

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SEA OTTER CLASSIC 2010Shimano has finally pulled the embargo and secret shroud off their new XT and SLX groups, and they’ve both gone to 10 speeds in the rear while keeping their triple chainrings up front.

“When we started developing the new groups, we didn’t set out to make a 10 speed set up just to do 10 speeds,” says Devin Walton, Shimano’s man of the media.  “It was about making the best possible drivetrain, and what we figured out was that 10 speed was the way to do that.

“It allowed us to have a 36T cassette while keeping a close ratio between the gears.  And in the front, it let us create more efficiency by tweaking the tooth ratios.”

The new system uses Shimano’s Dynasys moniker from the road side, and the end result is a more efficient and usable drivetrain that claims to improve the overall ride experience in many ways.

More info, specs and photos after the break…

shimano-2011-xt-10speed-dynasys-cassette04 shimano-2011-xt-10speed-dynasys-cassette01

By increasing the total range of the cassette with a giant 36T big cog, Shimano was able to narrow the ratio of the three front chainrings.  So while a 2×10 setup focuses on the range used by racers, Shimano’s 3×10 is set up for the rest of the mountain biking audience.


The big ring was reduced to 42T (from 44) and the granny was upped to 24T (from 22).  The middle ring remains at 32T.  Together, the closer range loses a little bit at the top end of the gear range, but most riders aren’t going to miss it.  Seriously, how often are you pounding through in a 44/11 combo anyway?

“A 44T is a lot of gear for a mountain bike,” says Walton. “A 42 is a lot more usable and lets you stay in the big gear longer.  Moving from a 22 to a 24 on the little gear reduces chain tension by about 10%, which reduces friction by about the same amount, thereby increasing efficiency by about that amount.”


“The larger diameter rings usually improve rear suspension performance, too,” Walton added, noting that many suspension designs are tailored to perform best in the middle and larger rings.  The new Dynasys gearing keeps you in the bigger rings longer, technically improving efficiency (by reducing chain friction) and suspension performance (assuming you’re not on a hardtail).  Put another way (from their press release):

Choosing a more closely spaced front gear set reduces the difference in chain angle between gears further reducing drive-train induced suspension movement. Something that quickly becomes more apparent, however is that a more closely spaced front gear set requires fewer, if any, rear recovery shifts when trying to shift sequentially – cadence is less impacted so pedaling remains more stable and the shifting interface is simplified.

The chain is also new and borrows from Dura-Ace’s asymmetrical design.  The outer plates are designed to glide up the chainrings, and the inner plates are designed to float up the cassette, making the traditionally harder shifts much easier.  I spun the pedals around on this bike and shifting seemed pretty smooth, but the real test will come when we get our demo set next month (breath: held).

The crankarms are the same, but the rings (obviously) and the spider are new.


Besides the obvious changes to the crankset and cassette, both front and rear derailleurs are new, as is the righthand shifter lever assembly.  All items are marked with the Dynasys logo to indicate that they’re 10-speed.  And, lest you be tempted to just add the 10 speed cassette, Shimano says you’re wasting your time and money…it’s designed as s system and you really need all of the components to make it work better.  Otherwise, you may add a gear, but you’re not adding performance, and it may actually degrade the overall experience trying to piece it into your current setup.


If you’re familiar with the current generation of XT and SLX, what you see here isn’t going to look terribly different.  In fact, there are few physical differences to the casual observer other than the addition of the Dynasys logo.


One difference is the cage length on the rear derailleur.  Despite gaining size at the upper end of the cassette, the reduction of the big ring up front makes for an overall more compact package, allowing the cage to be slightly shorter than the current long cage version.

shimano-2011-xt-10speed-dynasys-rderailleur02 shimano-2011-xt-10speed-dynasys-rderailleur01

shimano-2011-xt-10speed-dynasys-shifter01 shimano-2011-xt-10speed-dynasys-shifter03

shimano-2011-xt-10speed-dynasys-shifter04 shimano-2011-xt-10speed-dynasys-shifter02


The SLX group was not on hand for photography, but we’ll post some media-ready glamour shots as soon as we get our dirty little hands on them.  Click that pic above to enlarge to legible size for all the details in manufacturer marketing speak.


2011 Shimano Deore XT Specifications:
RD-M773 – XT Shimano Shadow Rear Derailleur

  • Low Profile Shimano Shadow rear derailleur design reduces the component profile by 15mm less than a traditional design in high gear.
  • Top normal spring design to mesh with the more common choice of RapidFire shifters for trail / all-mountain riding
  • Sealed bearing guide and tension pulleys
  • Available in medium and long cage (GS and SGS)
  • Total capacity: 43T (SGS), 35T (GS)
  • MSRP: $129.99

FD-M770/771-10 Front Derailleur Specific 10s cage design

  • Available in Top Swing, conventional, or E-type configurations to mount on most any frame
  • Adaptable clamp means one size fits all for 28.6, 31.8, 34.9 and multi-pull allows top or bottom cable pull
  • Set screws are angle outward for easier adjustment on some full suspension designs
  • Clamp band positions the same for 9 and 10s versions
  • Cage profiled for more tire clearance
  • MSRP: $59.99

SL-M770-10-R RapidFire Plus Shift Lever (rear)

  • Additional rear shifter option with 10s vs. 9s
  • Alloy main lever 2-way release trigger allows thumb or finger actuation
  • Two position clamp band for tune-able ergonomics
  • Multi-bearing construction for greater durability and reduced effort
  • Removeable optical gear display
  • MSRP: $99.99 (set, front lever same as 9s)

FC-M770-10 Front Chainwheel

  • Hollowtech II design maximizes stiffness while keeping weight to a minimum
  • Precision two-piece construction for perfect chainline and chainwheel alignment.
  • 42T-32T-24T
  • Carbon / Steel composite middle ring adds rigidity for better shifting, increases service life, and smoothly delivers powers to the cassette.
  • Outboard bearings maximize stability and stiffness
  • MSRP: $359.99

CS-M771-10 Cassette

  • Largest 6 cogs on two spiders for light and rigid construction
  • 11-13-15-17-19-21-24-28-32-36 and 11-13-15-17-19-21-23-26-30-34
  • Alloy lock ring
  • MSRP: $114.99

CN-HG94 Chain HG-X direction chain

  • Inner and outer plates feature asymmetrical design to optimize front and rear shifting
  • Zinc-alloy plated for maximum durability
  • Uses standard connecting pin
  • MSRP: $49.99
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13 years ago

I don’t get it? What is the point of going to a ten speed cassette if we aren’t gaining anything except more complexity and in fact loosing gear inches?

13 years ago

@alloycowboy: It’s XC-oriented, so I’d say it’s for pedaling/cadence efficiency. Most of the time your optimal power output is in a narrow range of cadence, so keeping it within that range can help, especially for longer events. That said, optimal power output isn’t a huge deal for everyday riding and it only varies by single percentage points anyway, so yeah, it is also just to make a buck on those that have to have the latest and greatest. I do agree with the article, though, in that I use my 22-32 more than a 44-11 in technical riding, so a reduction in gear inches at the low end is more beneficial than maintaining gear inches available on the high end.

13 years ago

Did they say anything about long-term durability of the new 10SPD chain?

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